$ { {3} \times \left[\begin{array}{rr}{4} & {0} \\ {2} & {0} \\ {4} & {1}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{3}\times{4} & {3}\times{0} \\ {3}\times{2} & {3}\times{0} \\ {3}\times{4} & {3}\times{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{12} & {0} \\ {6} & {0} \\ {12} & {3}\end{array}\right]}$